I have chalk brood in pretty well all my colonies and always have.... the oldest colony with it is 17 years.... ie my original colony.... if it hasn't killed them off in that time then I don't think it's worth worrying about. There are times when it is hardly noticeable and other times when it's worse but it's very unlikely to be terminal. I see it as being similar to eczema or hayfever in the sense that you/they learn to manage it. It's a fungal disease and as with most fungi, it thrives in damp conditions

I realise this may be controversial and is entirely unsubstantiated but I think chalkbrood is more an issue of hive environment rather than queen. I have only ever seen it when colonies haven't had sufficient bee numbers to support the frames/comb they have.
I suppose a queen with a high lay rate would sort this out but then so does allowing the colony to find it's own size.

Replacing the queen is the usual treatment, on the grounds that there is a genetic trait behind a susceptibility to chalk brood. I have no idea if this is indeed the case, although it would seem to be a reasonable hypothesis, given that the 'treatment' appears to work.

CB is not regarded as a serious problem, but given the choice, I would not want to breed from a queen with this tendency unless she had several strong, redeeming traits.

Conserving wild bees

Research suggests that bumble bee boxes have a very low success rate in actually attracting bees into them. We find that if you create an environment where first of all you can attract mice inside, such as a pile of stones, a drystone wall, paving slabs with intentionally made cavities underneath, this will increase the success rate.

Most bumble bee species need a dry space about the size a football, with a narrow entrance tunnel approximately 2cm in diameter and 20 cm long. Most species nest underground along the base of a linear feature such as a hedge or wall. Sites need to be sheltered and out of direct sunlight.